Add calendar selection dropdown and fix multi-calendar event display

- Add calendar selection dropdown to event creation modal
- Update EventCreationData to include selected_calendar field
- Pass available calendars from user info to modal component
- Initialize dropdown with first available calendar as default
- Fix backend to fetch events from ALL calendars, not just the first
- Update refresh_event to search across all calendars
- Events created in any calendar now properly display in UI

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/src/handlers.rs

@@ -39,11 +39,24 @@ pub async fn get_calendar_events(
         return Ok(Json(vec![])); // No calendars found
     }
     
-    // Fetch events from the first calendar
-    let calendar_path = &calendar_paths[0];
-    let events = client.fetch_events(calendar_path)
-        .await
-        .map_err(|e| ApiError::Internal(format!("Failed to fetch events: {}", e)))?;
+    // Fetch events from all calendars
+    let mut all_events = Vec::new();
+    for calendar_path in &calendar_paths {
+        match client.fetch_events(calendar_path).await {
+            Ok(mut events) => {
+                // Set calendar_path for each event to identify which calendar it belongs to
+                for event in &mut events {
+                    event.calendar_path = Some(calendar_path.clone());
+                }
+                all_events.extend(events);
+            },
+            Err(e) => {
+                // Log the error but continue with other calendars
+                eprintln!("Failed to fetch events from calendar {}: {}", calendar_path, e);
+            }
+        }
+    }
+    let events = all_events;
     
     // Filter events by month if specified
     let filtered_events = if let (Some(year), Some(month)) = (params.year, params.month) {
@@ -80,11 +93,23 @@ pub async fn refresh_event(
         return Ok(Json(None)); // No calendars found
     }
     
-    // Fetch the specific event by UID from the first calendar
-    let calendar_path = &calendar_paths[0];
-    let event = client.fetch_event_by_uid(calendar_path, &uid)
-        .await
-        .map_err(|e| ApiError::Internal(format!("Failed to fetch event: {}", e)))?;
+    // Search for the specific event by UID across all calendars
+    let mut found_event = None;
+    for calendar_path in &calendar_paths {
+        match client.fetch_event_by_uid(calendar_path, &uid).await {
+            Ok(Some(mut event)) => {
+                event.calendar_path = Some(calendar_path.clone());
+                found_event = Some(event);
+                break;
+            },
+            Ok(None) => continue, // Event not found in this calendar
+            Err(e) => {
+                eprintln!("Failed to fetch event from calendar {}: {}", calendar_path, e);
+                continue;
+            }
+        }
+    }
+    let event = found_event;
     
     Ok(Json(event))
 }